1. Technical Field
The invention relates to a device which is useful for rapidly dispensing precise quantities of a viscous material, preferably semi-solid in nature, such as various resins, solder paste, grease, etc. in exact locations. In particular, the invention relates to a compact, lightweight, hand-held device for accurately dispensing small drops or "shots" of material, e.g., about 0.5 cc, in a relatively rapid fashion.
2. Background Information
The dispensing of extremely small amounts or shots of semi-solid materials at precise locations in a rapid manner presents a challenge to those in the dispensing art due to the miniature solids contained in many of the materials to be dispensed, as well as the high viscosity of the materials. Various devices have been developed for the dispensing of precise amounts of such materials, such as air-driven syringes, peristaltic pumps, gear displacement arrangements and positive-displacement pumps. Although these devices do provide for the satisfactory dispensing of such materials, the equipment is relatively bulky and expensive, and is usually intended to be mounted on robots or at stationary work locations. Thus, the need exists for a lightweight, easily manipulated, hand-held, positive-displacement dispenser which will accurately and rapidly dispense very small shots of a semi-solid material at an exact location.
One type of dispenser for achieving this result is shown in U.S. Pat. No. 4,942,984, the contents of which are incorporated herein by reference. Although this dispenser achieves its desired results in a relatively simple manner, it requires the use of three separate incoming pressurized air lines for operating the movable pistons located internally in the hand-held housing. The present invention is an improvement upon the dispenser of U.S. Pat. No. 4,942,984, and enables the unit to be more compact and easily manipulated, and requires only two incoming air lines, both of which are located at the top part of the hand-held housing adjacent the incoming material supply line.